The restructuredText output includes both the parameter type and
the name for functions and function-typed members.  Do the same
for docbook.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>